Y and Al modified silicide coatings on an Nb-Ti-Si based ultrahigh temperature alloy prepared by pack cementation process
Y and Al modified silicide coatings on an Nb-Ti-Si based ultrahigh temperature alloy prepared by pack cementation process
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DOI：
10.1016/j.surfcoat.2011.07.056
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发表时间：
2011-10
影响因子：
5.4
通讯作者：
Ping Zhang;Xiping Guo
中科院分区：
文献类型：
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作者：
Ping Zhang;Xiping Guo
在Nb-Ti-Si基中温合金上，通过在1150°C下共沉积Si、Al和Y，制备了Y和Al改性的硅化物涂层。Al和Si的沉积在包埋渗过程中以顺序的方式发生。在初始阶段，沉积的元素主要是Al，具有非常少的Si，并且优先形成Al 3（Nb，X）（X表示Ti、Cr和Hf元素）层。在短时间的保持时间之后，Si开始沉积并且发生Si-Al共沉积。然而，这种Si-Al共沉积时间并不长。当1150°C保温时间大于1h时，Si沉积占主导地位。在1150°C下，涂层生长动力学遵循抛物线规律。在1150°C下保温10 h制备的涂层具有多层结构，外层为厚的（Nb，X）Si 2，中间层为薄的（Ti，Nb）5Si 4，内层为富Al，Cr。该涂层可保护Nb-Ti-Si基合金在1250°C空气中至少100 h不被氧化。涂层具有优异的抗氧化性能，主要是由于涂层表面形成了以TiO 2、SiO2和Al 2 O3为主的致密氧化膜。
Y and Al modified silicide coatings were prepared on an Nb–Ti–Si based ultrahigh temperature alloy by co-depositing Si, Al and Y at 1150°C for up to 10h, respectively. The deposition of Al and Si occurred in a sequential manner during the pack cementation process. At the initial stage, the element deposited was primarily Al with very little Si and an Al3(Nb,X) (X represents Ti, Cr and Hf elements) layer formed preferentially. After a short period of holding time, Si started depositing and Si–Al co-deposition took place. However, this Si–Al co-deposition period was not long. When the holding time was longer than 1h at 1150°C, Si deposition dominated the coating growth process. The coating growth kinetics at 1150°C followed a parabolic law. The coating prepared at 1150°C for 10h had a multi-layer structure, with a thick (Nb,X)Si2outer layer, a thin (Ti,Nb)5Si4middle layer and an Al, Cr-rich inner layer. The coating could protect the Nb–Ti–Si based alloy from oxidation at 1250°C in air for at least 100h. The excellent oxidation resistance of the coating was attributed to the formation of a dense scale mainly consisted of TiO2, SiO2and Al2O3.